fix disappearing popup box. fixes #188

Author: ButchersBoy

MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.PopupBox.xaml

@@ -14,14 +14,14 @@
     <converters:NullableToVisibilityConverter x:Key="InvertedNullVisibilityConverter" NullValue="Visible" NotNullValue="Collapsed" />
     <converters:BrushRoundConverter x:Key="BrushRoundConverter"/>
 
+    <Path x:Key="MaterialDesignPopupBoxToggleContent" 
+          x:Shared="False"
+          Data="M4.1239999,2.0625 C4.1239999,3.2015873 3.2008111,4.125 2.062,4.125 C0.92318883,4.125 0,3.2015873 0,2.0625 C0,0.9234127 0.92318883,0 2.062,0 C3.2008111,0 4.1239999,0.9234127 4.1239999,2.0625 z M4.1859999,8.0465 C4.1859999,9.1855873 3.2628111,10.109 2.124,10.109 C0.98518883,10.109 0.062,9.1855873 0.062,8.0465 C0.062,6.9074127 0.98518883,5.984 2.124,5.984 C3.2628111,5.984 4.1859999,6.9074127 4.1859999,8.0465 z M4.1859999,13.9215 C4.1859999,15.060587 3.2628111,15.984 2.124,15.984 C0.98518883,15.984 0.062,15.060587 0.062,13.9215 C0.062,12.782413 0.98518883,11.859 2.124,11.859 C3.2628111,11.859 4.1859999,12.782413 4.1859999,13.9215 z"                      
+          Fill="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType=wpf:PopupBox}, Path=Foreground}"
+          Margin="4 0 4 0"/>
+    
     <Style TargetType="{x:Type wpf:PopupBox}" x:Key="MaterialDesignPopupBox">
-        <Setter Property="ToggleContent">
-            <Setter.Value>
-                <Path Data="M4.1239999,2.0625 C4.1239999,3.2015873 3.2008111,4.125 2.062,4.125 C0.92318883,4.125 0,3.2015873 0,2.0625 C0,0.9234127 0.92318883,0 2.062,0 C3.2008111,0 4.1239999,0.9234127 4.1239999,2.0625 z M4.1859999,8.0465 C4.1859999,9.1855873 3.2628111,10.109 2.124,10.109 C0.98518883,10.109 0.062,9.1855873 0.062,8.0465 C0.062,6.9074127 0.98518883,5.984 2.124,5.984 C3.2628111,5.984 4.1859999,6.9074127 4.1859999,8.0465 z M4.1859999,13.9215 C4.1859999,15.060587 3.2628111,15.984 2.124,15.984 C0.98518883,15.984 0.062,15.060587 0.062,13.9215 C0.062,12.782413 0.98518883,11.859 2.124,11.859 C3.2628111,11.859 4.1859999,12.782413 4.1859999,13.9215 z"                      
-                      Fill="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType=wpf:PopupBox}, Path=Foreground}"
-                      Margin="4 0 4 0"/>
-            </Setter.Value>
-        </Setter>
+        <Setter Property="ToggleContent" Value="{StaticResource MaterialDesignPopupBoxToggleContent}" />
         <Setter Property="HorizontalAlignment" Value="Left" />
         <Setter Property="wpf:ShadowAssist.ShadowDepth" Value="Depth3" />
         <Setter Property="TextElement.FontWeight" Value="Normal" />